National Demographic Indicators SeriesData notes

Estimated resident population (ERP)

Estimated Resident Population is the official population of a Territorial Authority. It adjusts for the net undercount found in Census data, people overseas on Census night, and is updated annually based on the number of registered births, deaths, and an estimate of overseas, inter-region and intra-region migration.

While ERP is the most accurate measure of population at any point in time, it is subject to revision. Minor revisions are made each year to previous years' populations, and a final revision to the previous 5 years' results happens after each Census when the results are 'rebased' to the results of the most recent Census. This rebasing can alter populations significantly, depending on the Census findings, and indeed this is one of the reason we have a Census every 5 years.

Despite this revision, the ERP remains the official population count, and is used in allocation of funding at all levels of government, and the distribution of electorates by the New Zealand Electoral Commission.

Median age

Derived from the Census question:

'When were you born?'

This dataset shows the median age in years of the total population. The median is derived by arranging the entire population in an ordered list from youngest to oldest. It is the age of the middle person (or the average of the two in the middle in a list of even size).

Median is a useful summary measure of average age and very convenient for ranking areas – places with a large elderly population will have a higher median age while those with a lot of children and younger adults will have a lower median age. However a lot of detail of the population is lost. It is possible to have two areas with identical medians but very different age distributions.

If an answer to the Age question is not provided, Statistics New Zealand imputes the age of the respondent, so there is no "Not stated" category for this variable.

For more information on this topic, please see the information on Age(opens a new window) page on the Statistics New Zealand website.

Aged under 5

Derived from the Census question:

'When were you born?'

This dataset counts the number of persons aged 0-4 inclusive at the 2013 Census, as a percentage of total population in the area. A high percentage indicates an area of family formation (eg. first home buyers), or large families, or many single parent families. A low percentage may indicate an area with few families – it could be an elderly population, or a population of young adults attending university, for instance.

If an answer to the Age question is not provided, Statistics New Zealand imputes the age of the respondent, so there is no "Not stated" category for this variable.

For more information on the topic, please see the Age(opens a new window) page on the Statistics New Zealand website.

Aged over 65

Derived from the Census question:

'When were you born?'

This dataset counts the number of persons aged 65 years and over at the 2013 Census, as a percentage of total population in the area.
A high percentage indicates an area with a lot of retirees and elderly population. This may be due to people retiring to the area (common in coastal communities) or ageing in place in family households. A low percentage indicates a younger population, of young adults or families with children.

If an answer to the Age question is not provided, Statistics New Zealand imputes the age of the respondent, so there is no "Not stated" category for this variable.

For more information on the topic, please see the Age(opens a new window) page on the Statistics New Zealand website.

Māori population

Derived from the Census question:

'Are you descended from a Māori (that is, did you have a Māori birth parent, grandparent or great-grandparent etc)?'

People included in this category include all those who answered “Yes”.

This indicator presents the number of people of Māori descent, expressed as a percentage of the total population.

A person has Māori descent if they are of the Māori race of New Zealand; this includes any descendant of such a person. The term 'Māori descent' is based on a genealogical or biological concept, rather than on cultural affiliation to the Māori ethnic group. Information on cultural affiliations, or ethnicity, is collected in the census question on ethnic group. It is important to view this question in conjunction with the question about Ethnicity as some people who have Māori ancestry may not identify themselves ethnically as Maori. There is no reason to expect the populations stating Māori ethnicity to equate to those stating Māori descent in this question.

Māori in this context are inclusive of New Zealand Maori, but Cook Island Māori people are not included.

Overseas born

This indicator shows the number of people who were born outside of New Zealand based on their country of birth as a percentage of the total population.

Country of birth refers to the country where the person was born, and uses the name of the country at the time of the Census. Country is the current, short or official name of a country, dependency, or other area of geopolitical interest.

The term "country" is defined to include:

Independent nations recognised by the New Zealand Government.

Units which are recognised geographic areas;

Administrative subdivisions of the United Kingdom, and;

Overseas dependencies, external territories of independent countries.

Areas with a higher proportion of people born overseas are likely to have a high number of migrants, including recent arrivals. Areas with a low proportion probably have predominantly New Zealand-born populations.

Changed address in last 5 years

Derived from the Census question:

'Where does the person usually live?' and 'Where did the person usually live five years ago (on 5 March 2008)'.

This indicator measures the mobility of the population over the 5 year period ending on Census night, March 3rd, 2013. It presents the number of people who changed address at least once within this 5 year period, as a percentage of the total population aged 5 years or more.

People may have moved locally, around the country or from overseas.

A high percentage indicates a mobile population, with people staying a relatively short time. This is often associated with inner city, rental and student areas with a young population.

A low percentage indicates a stable, sedentary population, with people staying in place over many years. This is often associated with older suburban and rural populations and full home ownership.

Degree or higher qualification

Derived from the Census questions:

'What is your highest secondary school qualification?', 'Apart from secondary school qualifications do you have another completed qualification?', and 'Print your highest qualification level and the main subject.'

This indicator looks at the number of people with a university level qualification, as a percentage of the total population aged 15+.

University qualifications are defined as non-school qualifications which are Bachelor Degrees, Graduate Certificate or Diplomas, Masters Degrees and PhDs. Only the highest qualification is counted.

Qualifications attained overseas may be counted, if they are within the scope of the New Zealand Classification of Education.

Educational qualifications are highly correlated with income and socio-economic advantage. A high proportion of university qualifications indicate a highly educated area, most likely with relatively high incomes. Low proportions of university qualifications may be correlated with lower incomes, or older populations (university attendance has increased in recent decades).

Public transport to work

'On Tuesday 5 March, what was the one main way you travelled to work – that is, the one you used for the greatest distance?'

This indicator measures the number of people who took public transport to work on Census day, 2013, as a percentage of the total employed population aged 15+.

The method of travel is a single response variable. If a person travelled using multiple methods, they are instructed to record only that method which they used for the longest distance.

Please note that method of travel to work relates only to one particular day and is not necessarily indicative of a “usual” method of travel.

This indicator is likely to be much higher in areas with a large availability of public transport options, and a high proportion of the population working in central city areas, which are easily accessed by public transport. Areas with poor availability of public transport or people working in dispersed areas are likely to have lower public transport use. Areas with people living very close to their workplace may also have low public transport use due to a high proportion walking or riding bicycles to work.

Index of Deprivation

The Deprivation indexes are derived from a calculation using a range of variables from the 2013 Census of Population and Dwellings which represent nine dimensions of socio-economic disadvantage to create a summary deprivation score. The nine variables (proportions in small areas) in decreasing weight in the index are:

1

Communication

People aged <65 with no access to the Internet at home

2

Income

People aged 18-64 receiving a means tested benefit

3

Income

People living in equivalised* households with income below an income threshold

4

Employment

People aged 18-64 unemployed

5

Qualifications

People aged 18-64 without any qualifications

6

Owned home

People not living in own home

7

Support

People aged <65 living in a single parent family

8

Living Space

People living in equivalised* households below a bedroom occupancy threshold

9

Transport

People with no access to a car

* Equivalisation: methods used to control for household composition.

For the purpose of comparison, the Social Deprivation Index is presented as a scale, ranking small areas from the least deprived to the most deprived. The mean is 1000 index points and the higher the number the greater the deprivation.

The Social Deprivation Index is used in the measurement and interpretation of socioeconomic status of communities for a wide variety of contexts such as needs assessment, resource allocation, research and advocacy.

Note that the deprivation index applies to areas rather than individuals who live in those areas.

For the index, a lower the number indicates a less deprived area; a higher number indicates a more deprived area.

Median household income

Derived from the Census question:

'From all sources of income identified, what will the total income be that you got yourself, before tax or anything was taken out of it, in the 12 months that will end on 31 March 2013?'

Household income data presents the total combined weekly incomes of all persons over the age of 15 in the household. Households where one or more personal incomes were not stated or a resident over 15 was away on Census night are included in 'Not Stated'. In these cases, the aggregate of all stated individual incomes would be less than the true household income so these households are excluded from the classification.

Median Household income is an imputed midpoint obtained by arranging all reported household incomes in an ordered list and taking the middle value. Because incomes are collected in ranges, the range containing the middle value may be broad, and the approximate dollar value of the median is calculated by assuming a uniform distribution of incomes within that range and calculating the point at which the 50th percentile of population distribution would fall within this range based on this assumption, and the cutoffs of the surrounding 2 ranges.

As individual income is collected in ranges, in order to calculate household income, a dollar value has to be imputed by the Statistics New Zealand to each range, then the individual incomes are aggregated, and output into ranges again. There is an inherent uncertainty in this process, as well as the calculation of medians from the derived ranges, so household incomes should only be treated as a guide to the income level in an area, not an exact calculation.

Average household size

'Average household size’ consists of the number of persons counted in private dwellings divided by the number of occupied private dwellings on Census night.

It is a measure of the mean number of persons per private household and excludes non-private dwellings.

Average household size is likely to be high in family areas with large numbers of children, large houses, or many people sharing dwellings in group households. It is likely to be low in elderly areas with a lot of 1 and 2 person households, and areas with very small dwellings (0-1 bedroom) and a lot of young people living alone.

Large dwellings

Derived from the Census:

'How many bedrooms are there in this dwelling?'

This indicator measures the amount dwellings with 4 bedrooms or more as a percentage of total dwellings in the area.

Access to the internet

Derived from the Census:

'Mark as many spaces as you need to show which of these are available here in this dwelling; a cellphone/mobile phone (that is here all or most of the time), a telephone, fax access, Internet access, none of these.'

This indicator measures the amount dwellings with access to the internet as a percentage of total dwellings in the area.